Search

Microcapsule technology is a promising approach for enhancing the self-healing ability of asphalt pavements. In this study, the self-healing behavior of melamine-urea-formaldehyde (MUF) microcapsules was investigated. The microcapsules were synthesized using an in situ polymerization method. The proposed healing indicators, combined with fluorescence tracing technology, were used to evaluate the release behavior and sustained repair effect of the microcapsules at different damage levels, healing intervals, aging degrees, and healing temperatures. The results showed that most microcapsules survived at low damage levels, whereas larger microcapsules were more likely to rupture and release the rejuvenators. The sustained self-healing effect of the microcapsules could effectively repair internal damage within the asphalt pavement over an extended service life. Aged asphalt was particularly susceptible to the activation of microcapsules, leading to increased self-healing and the provision of additional rejuvenators for damaged asphalt mastic. Additionally, the self-healing of asphalt mastic with microcapsules had a critical temperature threshold. Microcapsules could enhance the fatigue and self-healing performance of asphalt mastic only when the healing temperature was below a certain value; otherwise, they may lead to adverse effects. The critical healing temperature threshold for thin-film oven testing (TFOT)-aged asphalt increased from approximately 30°C to about 45°C after PAV aging. This study provides a better understanding of the self-healing behavior of microcapsule asphalt, as well as the factors affecting the release behavior and sustained repair effects of the microcapsules. These results can be used to optimize the design and implementation of microcapsule technology to enhance the durability and sustainability of asphalt pavements. [ABSTRACT FROM AUTHOR]

Investigations of the physicochemical interactions occurring at asphalt–mineral filler interfaces are important in understanding the mechanisms that govern the mechanical attributes of asphalt mixtures. The measurement of the adsorbed asphalt film thickness (AAFT) provides valuable insights into the underlying physicochemical interactions. However, direct measurement of AAFTs through laboratory tests poses considerable challenges. This study describes AAFT calculation methods based on the N-phase model and Christensen-Lo model. The AAFTs of different types of asphalt mastic were calculated by conducting dynamic shear rheology (DSR) tests. To ascertain the physicochemical mechanisms governing interactions between the asphalt and mineral fillers, fourier transform infrared (FTIR), Brunner−Emmet−Teller (BET), scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies were carried out. The findings revealed that the AAFT was related to the testing temperature, frequency, filler content, and type. The AAFTs for asphalt mastics with different filler types decreased in the order (from thick to thin) of coal gangue filler, limestone filler, and fly ash. The external specific surface areas and chemical compositions of the mineral fillers emerged as the primary factors influencing their physicochemical interactions with the asphalt. The coal gangue asphalt mastic exhibited a smaller and denser AFM bee structure, which was attributed to the physicochemical interactions. The findings of this research contribute to the selection of mineral fillers and filler/binder ratios that can be utilised for optimising the design of asphalt mixtures comprising different types of fillers. [ABSTRACT FROM AUTHOR]

The rheological and dielectric characteristics of asphalt mastics with different ratios of limestone filler were analyzed and compared with each other for road pavement applications. The dielectric properties of asphalt mastics are studied as a function of frequency (0,1–106 Hz) at different temperatures ((-)40°C−40°C). The glass transition temperature and the relaxation behaviour were determined by Vogel–Fulcher-Tamman and Cole–Cole equations, respectively. The free volume fraction was calculated by the Dolittle equation. The filler ratio dependence of the dielectric properties was attributed to the variation of the void fraction. This result was related to the glass transition temperature and ductility. The sample with 6 wt% limestone filler showed the highest dielectric constant value among all samples for all temperatures due to the excellent adhesion between binder and filler. Consequently, it was determined to be the optimum value to design hot mix asphalt for use in territories with high-temperature differences. [ABSTRACT FROM AUTHOR]

Used engine oil recycling produces acid sludge as a by-product of the acid-clay treatment. It is classified as hazardous waste material. This paper introduces a novel material named PS (powdery sludge) by functionalising the acid sludge. PS was used in a dry method to replace fine aggregates of the asphalt mixture. The effect of adding PS was investigated on the rheological behaviour of asphalt mastics by using dynamic shear rheometer for performing frequency sweep and multiple stress creep and recovery tests, bending beam rheometer, differential scanning calorimetry, and Fourier transforms infrared spectroscopy tests. Adding PS makes the mastic softer at low temperatures and stiffer at high temperatures, causing it up to 5 and 1.38 times more resistant to rutting and fatigue, respectively. Also, PS reduces temperature sensitivity, aging potential, and moisture sensitivity. Therefore, using PS as a replacement for siliceous aggregates in cold, moderate, and tropical regions is recommended. [ABSTRACT FROM AUTHOR]

This research conducted a comprehensive assessment of how aging processes and the powder to binder ratio (P/B ratio) influence asphalt mortar's performance. Analysis demonstrated that all tested performance metrics significantly differed (P<0.05), signifying a notable effect of the aging process, particularly long-term thermal oxidation aging, on key properties such as ductility and the complex shear modulus (G*). Adjusting the P/B ratio enables precise control over the rate of aging and the asphalt mixture's functional characteristics. The optimal P/B ratio, found to be between 0.8 and 1.0, effectively balances aging properties with mechanical strength. Moreover, a detailed analysis of the four main asphalt components shed light on aging's effects on both the composition and functionality of asphalt, highlighting the critical role of component dynamics in designing and assessing asphalt mixtures. Additionally, the study introduces a predictive model that uses linear regression to compute five parameters (β0 to β4), forming equations for various performance metrics. This facilitates optimized selection and combination of asphalt components at the design stage. [ABSTRACT FROM AUTHOR]

Abstract Although the fatigue properties of asphalt materials have been extensively studied, the relationship between the rheological properties and road performance of asphalt mixtures remains underexplored. In this study, we have examined the relaxation properties of asphalt binders through relaxation tests conducted on asphalt and its mastic under different conditions. A repeated stress relaxation-recovery test is designed for assessing both the relaxation and elastic properties, and a set of reasonable test parameters is recommended, thereby establishing a novel test method for measuring the relaxation and elastic behaviors of asphalt. In addition, we have proposed evaluation indexes, such as relaxation time, relaxation rate, and strain recovery rate, to assess the stress relaxation performance and strain recovery ability. It is observed that the relaxation rate and strain recovery rate of the material can be used to characterize the material’s relaxation and elasticity properties, respectively. Thus, the proposed indexes can be used to comprehensively evaluate the viscoelastic performance of the material. The fatigue performance of the selected materials is further examined using the linear amplitude sweep (LAS) test, and the correlation between the relaxation properties and fatigue performance (as indicated by fatigue parameters) is explored. Furthermore, a fatigue performance prediction equation based on the repetitive stress relaxation-recovery test is established. The findings reveal a strong correlation between the relaxation properties and fatigue performance, suggesting that the stress relaxation test can accurately assess the fatigue performance of asphalt materials.

Asphalt mortar is a mixture of asphalt mastic and fine aggregates (<2.36 mm) in asphalt concrete. Accurately predicting the complex modulus of asphalt mortar is essential to further estimating asphalt concrete's viscoelastic properties. However, existing analytical and numerical mesomechanical models generally underestimate the dynamic moduli of asphalt mortar and overestimate its phase angles, especially at high temperatures and low frequencies, because the solidifying reinforcement mechanisms are not considered. Also, the commonly used mesoscale division method for asphalt mortar, which takes asphalt mastic as the matrix phase, may lead to computational inefficiencies due to the presence of numerous fine aggregates. To address these issues, this study proposed a coarse asphalt mastic-based three-dimensional (3D) mesostructure model of asphalt mortar considering a conjunctive shell mechanism of interface transition zones (ITZs). A new mesoscale division method was proposed for asphalt mortar, which defines the coarse mastic incorporating the aggregates smaller than 0.6 mm as the matrix phase. A conjunctive shell mechanism of ITZs was proposed to account for the solidifying reinforcement effect due to the overlapped ITZs of closely adjacent aggregates. The results indicate that the overlapped ITZs led to the formation of the agglomeration networks of aggregates. The introduction of conjunctive shell mechanism of ITZs enabled accurate prediction of the complex modulus of asphalt mortar even at low frequencies and high temperatures and revealed the solidifying behaviors of asphalt mortar. The computational efficiency was substantially improved by introducing the coarse mastic matrix. [ABSTRACT FROM AUTHOR]

Rheological assessment of mastics can provide better insight into estimating the resistance of the mixtures against fatigue since it is the real binder coating the aggregate skeleton. The primary purpose of this study is to assess the suitability of MSCR test to analyze the fatigue resistance of bituminous mastics prepared using waste (GP and KS), composite (GL), and conventional SD fillers. Additionally, the fatigue resistance of mastics was also determined using Linear amplitude sweep (LAS) and fatigue parameter analysis and all results were compared with the fatigue performance of bituminous mixes. The correlation between mixtures and mastics prepared with SD filler is very strong in all the approaches, that is, LAS (R2 = 0.92), % R (R2 = 0.93), and fatigue parameter (R2 = 0.95). For GP, it is strongest in % R (R2 = 0.78) whereas for KS the correlation was highest in the LAS test (R2 = 0.92) which shows that correlation analysis yields mixed results. The ranking methodology showed a similar ranking between fatigue life of mixes and the percent recovery whereas the ranking of other parameters was different. The test results showed that the % R can also be a promising parameter for the fatigue analysis of the bituminous mastics in addition to the existing fatigue damage parameters. [ABSTRACT FROM AUTHOR]

Copyright of Roads & Bridges / Drogi i Mosty is the property of Road & Bridge Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Silicon carbide powder, as a high-performance microwave-absorbing material, can be used for self-healing of microcracks in asphalt pavements, which is promising to lift the limitation of the application of microwave heating technology in road maintenance. The primary adhesive skeleton in asphalt mixtures, known as asphalt mastic, plays a crucial role in determining the overall properties of the mixtures. In this study, conventional limestone asphalt mastic and silicon carbide powder asphalt mastic with high microwave absorption capacity were designed and prepared using varying filler-bitumen ratio (FBR). The performance and properties of the filler were tested by XRD and SEM. The microwave heating test and DSR test were carried out on the fillers and asphalt mastics to study the microwave heating properties and rheological properties. Based on rheological properties, initial and optimal temperatures for self-healing are determined. The results show that the addition of silicon carbide powder had a significant increase in the initial self-healing temperature of asphalt mastic, but had little effect on the optimal self-healing temperature. Moreover, the difference in temperature to achieve the same rutting factor (1 or 10 kPa) is not significant. These indicate that it is feasible to consider silicon carbide powder as a filler in asphalt mixtures from the point of view of self-healing temperature. The exceptional microwave absorption capabilities of silicon carbide powder boost the microwave absorption of silicon carbide asphalt mastic, significantly reducing the time required to reach the necessary self-healing temperature. Overall, silicon carbide powder can be used in road engineering to enhance the microwave absorption properties of asphalt mixtures, which advances the application of microwave maintenance technology in road engineering. [ABSTRACT FROM AUTHOR]

The sewage sludge ash (SSA) is characterized as a by-product used in the pavement industry to mitigate the environmental risks, enhance the landfill capacity and conserve the non-renewable resources. This research utilized SSA as a filler substitute in asphalt mastic, and its performance-based properties from low towards high temperatures were evaluated. For this goal, the physical and chemical properties of SSA and rock powder (used as base filler) were determined using BET surface area measurement, X-ray fluorescence, and scanning electron microscopy tests. The performance of base and SSA-modified asphalt mastics in four filler/bitumen weight ratios (0.6, 0.8, 1, and 1.2) was investigated using dynamic shear rheometer, multiple stress creep and recovery, linear amplitude sweep, and bending beam rheometer tests across a wide temperature range. The results indicate that SSA has a higher specific surface area, better bitumen absorption, and lower density compared to the base filler. Additionally, unlike the acidic nature of the base filler, SSA possesses strong basic properties, leading to a stronger chemical bond with bitumen and enhanced resistance to aging, particularly at high temperatures. Moreover, the lower density of SSA escalates the amount of filler per unit volume of the SSA-modified asphalt mastic, leading to the increased stiffness and elasticity. This trend improves resistance to permanent deformation and cracking at medium temperatures, although it has an adverse effect on performance of mastic at low temperatures. Moreover, due to the improved performance of SSA-modified asphalt mastic, this study can contribute to the sustainable development of the pavement industry.

The primary objective was to evaluate the effects of particle morphology and size of mineral fillers on mastic rheological and creep properties. Experimentally, eight fillers prepared using the same grinding procedure were characterized. Dynamic shear rheometer and bending beam rheometer tests were employed to evaluate mastic rheological and creep behavior, respectively. Numerically, a dynamic viscoelastic model and Burgers creep damage model based on fractional derivatives were established. Results demonstrate that the datasets agree well using fewer model parameters, which can illustrate the availability of the proposed numerical method for the response of all analyzed mastic specimens. As the particle size decreases, material parameter and fractional order are increased by 10.31%, 23.45%, 24.72% and 0.68%, 1.46%, 1.48% for mastics containing limestone filler; and that are increased by 7.07%, 15.38%, 38.06% and 0.76%, 0.85%, 1.18% for mastics with granite filler at 45 °C, respectively. Apart from 150 to 200 mesh size range, the mastic with granite filler is less prone to creep damage accumulation inside the specimen than that containing limestone filler during the loading process. As the particle size increases, relaxation time is rapidly increased by 5.41%, 26.35%, 27.99% and 5.55%, 20.98%, −1.33% for limestone filler-asphalt mastics and granite filler-asphalt mastics, respectively. Moreover, form factor is the determining influential factor for mastic anti-rutting performance, temperature susceptibility and creep damage, while fractal dimension is the most relational factor affecting mastic dissipation capacity, regardless of filler lithology. All the results are conducive to designing mineral filler that fabricates mastic with the desired property.

The properties of asphalt mastic are crucial in determining the moisture sensitivity of asphalt mixtures, but the adhesion performance of the mastic has not been quantitatively described. To address this gap, this study calculated the asphalt mastic surface energy using the equation-of-state method, and established a moisture sensitivity (MS) index based on it. The effectiveness of this index was verified through Marshall testing. First, the surface energy of asphalt and filler was measured, and the critical volume fraction of the mastic was determined using the two-point method. Second, the interaction parameters of asphalt and filler were calculated using the equation-of-state method, and the surface energy of the mastic was obtained. Then the MS index was established to evaluate the moisture sensitivity of asphalt mixtures. This new index utilizes the surface energy and aggregate to quantitatively evaluate adhesion, considering the specific surface area of the aggregate and the thickness of asphalt film. Finally, the MS was validated through Marshall tests of asphalt mixtures. The results demonstrated that the MS obtained by the calculated surface energy exhibits a strong linear correlation with the moisture sensitivity of asphalt mixtures. The goodness of fit reached above 0.90 and the highest was 0.965. This study provided a novel approach to characterize the moisture sensitivity of asphalt mixtures. [ABSTRACT FROM AUTHOR]

To evaluate the possibility of using phosphorus slag powder instead of mineral powder as a filler in asphalt mastic, this study investigates the micro-characteristics of phosphorus slag powder and its viscoelastic mechanical properties in asphalt mastic. A systematic approach combining macro and micro test methods was used to analyze the physical and surface characteristics, void structure, and surface energy of phosphorus slag powder. The viscoelastic mechanical properties of phosphorus slag powder were evaluated using appropriate indexes. Meanwhile, the correlations between and limitations of various evaluation indexes and the high-temperature rheological properties were identified. The results demonstrate that phosphorus slag powder exhibits low density, small overall particle size, difficulty in forming agglomerates, developed pores, large specific surface area, and high surface energy, which is suitable for replacing mineral powder as a filler in asphalt mastic. The main factors affecting the viscoelastic properties of asphalt mastic are the particle size and dosage of phosphorus slag powder. Generally speaking, phosphorus slag powder asphalt mastic with particle sizes ≤ 18 μm exhibits the best performance. In practical engineering applications, the appropriate dosage (7%, 10%, 13%) can be selected based on different regions and specific design and construction requirements. Additionally, zero-shear viscosity (ZSV), non-recoverable creep compliance (Jnr), and creep recovery percentage (R) exhibit a strong correlation with the high-temperature rheological properties of asphalt mastic. At the same time, the rutting factor (G*/sin δ) presents certain limitations. [ABSTRACT FROM AUTHOR]

Incorporating iron tailings (ITs) into asphalt represents a new method for waste-to-resource conversion. The objective of this study is to evaluate the fatigue performance of ITs as fillers in asphalt mastic and investigate the interaction and interfacial adhesion energy between asphalt and ITs. To achieve that, the particle size distributions of two ITs and limestone filler (LF) were tested through a laser particle size analyzer; the morphology and structure characteristics were obtained by scanning electronic microscopy (SEM), the mineral compositions were conducted through X-ray diffraction (XRD), and the chemical compositions were tested through X-ray Fluorescence Spectrometer (XRF). Furthermore, the fatigue properties of asphalt mastic and the interaction between asphalt binder and mineral fillers (ITs and LFs) were evaluated by Dynamic Shear Rheometer (DSR). The interfacial adhesion energy between ITs and asphalt binder were calculated through molecular dynamics simulation. In the end, the correlation between the test results and the fatigue life is established based on the gray correlation analysis, the environmental and economic benefits of iron tailings asphalt pavement are further evaluated. The results show that the particle size distribution of ITs is concentrated between 30 μm and 150 μm, and the main component is quartz. ITs have rich angularity and a higher interaction ability with asphalt. The adhesion energy of iron tailings filler to asphalt is less than that of limestone. The correlation degree of the interfacial adhesion energy and interaction between asphalt and mineral filler with asphalt mastic fatigue life is close to 0.58. Under the combined action of interaction ability and interfacial adhesion energy, the fatigue life of IT asphalt mastic meets the requirements. ITs as a partial replacement for mineral fillers in asphalt pavement have great environmental and social effectiveness. [ABSTRACT FROM AUTHOR]

The fatigue characteristics of BND 60/90 grade bitumen, asphalt mastic (AM), modified bitumen (MB), and ternary mixtures (bitumen–filler–modifier) (modified asphalt mastic (MAM)) have been studied. Mineral powder (MP) with a bitumen : MP ratio of 2 : 1 and 1 : 1 has been used as a filler in AM and MAM. Active powder of discretely devulcanized rubber (APDDR) obtained by means of high-temperature shear grinding was used as a modifier in MB and MAM in an amount of 12.5% of APDDR with respect to the weight of bitumen. The positive effect of APDDR exerted on the fatigue life of bitumen and asphalt mastic has been shown. Such fatigue parameters as postpeak pitch angle and τmax/ determined from τ(γ) curves in a linear amplitude sweep test are promising for the ranking of modified samples containing a network of bonds. [ABSTRACT FROM AUTHOR]

To verify the feasibility of applying dry flue gas desulfurization ash (DFGDA) to asphalt pavement materials, the asphalt mastic (filler and asphalt composition) prepared by adding different proportions of DFGDA and LSP (limestone powder) into 70# matrix asphalt was studied experimentally. The asphalt mastics were subjected to the penetration test, the softening point test, and the ductility test. Moreover, the rheological properties of asphalt mastic were evaluated with dynamic shear rheometer (DSR) tests and bending beam rheometer (BBR) tests. An interaction ability index C-value based on the Palierne model was proposed to evaluate the interaction ability between DFGDA and asphalt. The influence of DFGDA asphalt on the interaction ability of matrix asphalt was observed and evaluated using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results showed that with the increasing proportion of DFGDA, the penetration of asphalt mastic gradually decreased, the softening point increased, and the ductility slightly decreased. At the same temperature, the dynamic shear modulus G* of the asphalt mortar significantly increased with increasing DFGDA content. The incorporation of DFGDA negatively affected the low-temperature plastic deformation resistance of asphalt, but the impact was weakened with the growing DFGDA amount and the powder mastic ratio. The combination mode of DFGDA and matrix asphalt depends on the physical blending, and their interaction ability mainly depends on the miscibility between DFGDA and matrix asphalt. In conclusion, DFGDA can be utilized as a novel filler in asphalt pavement materials. [ABSTRACT FROM AUTHOR]

The continuous growth of industrial solid waste production has generated many environmental problems. We evaluated the potential of industrial solid waste as a substitute filler in asphalt mastic, with the aim of increasing the use of sustainable road construction materials. In this study, X-ray fluorescence spectroscopy (XRF) and scanning electron microscopy (SEM) were used to characterize the oxide composition and micromorphology of limestone (LS), red mud (RM), steel slag (SS), and ground granulated blast-furnace slag (GGBFS). Four asphalt mastics containing LS, RM, SS, and GGBFS with a filler-to-binder weight ratio of one were prepared. An evaluation of the rheology and wetting of the solid-waste-filler asphalt mastic was conducted using a frequency sweep, temperature sweep, linear amplitude sweep (LAS), multiple stress creep and recovery (MSCR), and surface free energy (SFE) methods. The results showed that SS increased the complex modulus, elastic component of the asphalt mastic and decreased the nonrecoverable creep compliance at stress levels of 0.1 and 3.2 kPa, which improved the rutting resistance of the asphalt mastic and reduced deformation under high-temperature conditions. The RM and GGBFS increased the fatigue performance of the asphalt mastic under strain loading, enhanced its fatigue life, and maintained good performance under long-term loading. The dispersive component of the SFE parameter of the solid-waste-filler asphalt mastic was larger than the polar component for the largest share of the surface energy composition. The SFE of the asphalt mastic prepared from the industrial solid-waste filler was reduced; however, the difference was insignificant compared to the limestone asphalt mastic. Solid-waste-filler asphalt mastic has performance characteristics, and its actual application can be based on different performance characteristics to select an appropriate solid-waste filler. The results of this study provide new technological solutions for solving the utilization rate of solid waste materials and sustainable road construction in the future. [ABSTRACT FROM AUTHOR]

The volume filling ratio and type of filler significantly influence the rheological and mechanical properties of bituminous composites. This effect can stem from either chemical interactions between the filler and bitumen or simple physical phenomena. Understanding the influence of filler on asphalt mastic performance is crucial for comprehending the behavior of asphalt mixtures. This study employs both experimental and numerical modeling approaches. The rheological properties of asphalt mastic samples made with pure bitumen and limestone filler at various filler contents were determined using frequency sweep tests. The experimental results indicated that increasing the volume filling ratio in asphalt mastic leads to non-linear changes in the values of the complex shear modulus (G*) and phase angle (δ), known as the stiffening phenomenon. Considering the concept of transitional zone between filler and bitumen, a parameter called Effective Volume Filling Ratio (EVFR) was introduced to explain this phenomenon. To predict the viscoelastic behavior of asphalt mastic based on the mechanical properties of bitumen and filler, finite element method (FEM) simulations were utilized. The accuracy of these models was evaluated by calculating the relative difference between the experimental complex shear modulus (G*) and the complex shear modulus predicted by the model. Results of this evaluation indicated that incorporating the EVFR into the numerical model can significantly enhance the accuracy of the predictions for viscoelastic behavior of asphalt mastic samples. [ABSTRACT FROM AUTHOR]

A mechanical method is presented which helps to recover asphalt mastic from asphalt mixture without any chemical agent. It may be used as a surrogate to the current chemical extraction method when asphalt mastic shall be recovered from the asphalt mixture. The presented approach is based on granulation and sieving techniques. For the purpose of validation, the method is compared to the standard chemical extraction method which uses a chemical agent to recover the asphalt binder from the mineral aggregates. Both methods are compared in terms of recoverable amount of mastic, and of filler/binder ratio, of reproducibility, and of suitability of the recovered mastic sample for subsequent temperature and frequency sweep (T-f sweep) tests using a Dynamic Shear Rheometer (DSR). [ABSTRACT FROM AUTHOR]

The article presents the results of testing the asphalt binder modified with SBS copolymer (5%) and its mixture with mineral fillers called asphalt mastics. The aim of the research and analysis was to check the possibility of using an organic additive in the form of imidazolines and to assess their impact on the viscoelastic properties of the obtained asphalt mastics. The main advantage of using imidazoline is the increased resistance of asphalt mixtures to low-temperature cracking at the top of the road route and reducing its maintenance costs. Based on the examination of the adhesion of the binder with the addition of various imidazolines to the aggregate, a selection was made from six analyzed subtypes. One of them was selected for further research. The tests were carried out in a dynamic shear rheometer in a wide temperature range from −36 °C to 82 °C, determining the most important parameters of the tested materials, i.e., dynamic shear modulus (|G*|), phase angle (δ) and the non-recoverable creep compliance (Jnr). The test results and their analysis confirmed the beneficial effect of imidazoline on the viscoelastic properties of mastics in the low-temperature range, even at the lowest content of 0.2%. Based on the results of the determination of Jnr and |G*|/sinδ in the range of high operating temperatures, no significant deterioration in permanent deformation parameters was observed. Moreover, the use of imidazoline reduces technological temperatures during the production of HMA used in the pavement and, therefore, reduces CO2 emissions into the atmosphere. [ABSTRACT FROM AUTHOR]

Cotton straw, corn straw, waste bamboo and bagasse were used to prepare plant fibers in this work. The micro morphology, chemical composition and thermal stability of plant fibers were studied. The rheological properties of asphalt mastic were tested by dynamic shear rheometer and bending beam rheometer. The results show that cotton straw fibers, corn straw fibers and bagasse fibers have the structure with cavity tubular, while bamboo fibers and lignin fibers exhibit the solid structure in micron scale. The composition of plant fibers is different, which affects the thermal decomposition rate of fibers. After adding fibers, the high-temperature rheological properties are strengthened significantly. The rutting factor at the initial test temperature is increased by 23.8%-75.7%, and the recovery is increased by 9.4%-18.5%. The low temperature performance decreased slightly, but the effect of plant fiber types is not significant. [ABSTRACT FROM AUTHOR]

Recycled aggregate (RA) and recycled concrete powder (RCP) hold significant potential as environmentally sustainable raw materials for asphalt mixtures. In this study, a comprehensive investigation was conducted on the bonding properties between RA and RCP-filled asphalt mastic (RCPAM). This investigation utilized an image processing-assisted modified water boiling test, binder bond strength (BBS) tests, and the surface free energy (SFE) method. The results indicate that the boiling water test method, even with the assistance of 2D image processing analysis, cannot adequately evaluate the adhesive characteristics of the RA-RCPAM interface. This limitation could be attributed to the relatively small number of samples tested and the significant variation in surface properties of RA. Increasing both the filler-to-asphalt (F/A) ratio and RCP replacement ratio adversely affected the interfacial bond strength of the RA-RCPAM interface. On the other hand, an increase in RA surface roughness contributed to a higher bond strength. Based on the experimental results, a best-fit multivariate mixed model was proposed to predict the interfacial bond strength between RCP-filled asphalt mastic and recycled aggregate within a given range of RCP replacement ratio, surface roughness, and filler-to-asphalt (F/A) ratios. The analysis of SFE suggested that moisture damage to RCPAM was caused by both cohesive and adhesive failure. Additionally, the minimal impact of adhesion work in wet condition with increasing RCP content suggested that adhesion failure energy was only marginally affected by the inclusion of RCP, even in the presence of moisture. These findings are expected to enhance the understanding of interfacial adhesion characteristics and moisture susceptibility of the RA-RCPAM interface.

Asphalt mastic is a binary composite in which the bitumen matrix is embedded with filler particles. By taking interparticle interactions and the effects of bitumen origins and filler types into account, this research seeks to achieve a higher predictive precision of the modulus of asphalt mastics using micromechanical models. To achieve this goal, five classical micromechanical models and the Ju-Chen model (JCM) that effectively considers interparticle interactions were adopted to predict the moduli of 25 kinds of asphalt mastics composed of five bitumen origins and five filler types. The results show that the prediction accuracy of the general self-consistent model (GSCM) is the highest among the classical models, which is close to the accuracy of JCM (uniform) with the uniform distribution assumption for the radial distribution function. The JCM (P-Y) with the Percus-Yevick (P-Y) distribution assumption has the highest accuracy of all models, with average goodness of fit of 0.984 for all asphalt mastics. The dilute model (DM) exhibits higher accuracy in two bitumen with smaller low-temperature moduli, whereas the other five models in this study demonstrate higher accuracy in the other three bitumen with bigger low-temperature moduli. For the two models with the highest accuracy, the GSCM and JCM, the filler types have basically no effect on the prediction accuracy of these models. For other models except for GSCM and JCM, the smaller volume fractions of fillers lead to higher prediction accuracy, which can be attributed to the lower filler concentrations in asphalt mastics exhibiting weaker interparticle interactions. This study provides a certain reference for the performance prediction of asphalt mastic composites. [ABSTRACT FROM AUTHOR]

Reclaimed asphalt pavement (RAP) has been widely utilized because it is an environmentally friendly and economical material. The performance of recycled asphalt mixtures will deteriorate gradually with the secondary aging process of asphalt, including the self-healing property. To further understand the self-healing characteristics of asphalt after secondary aging, taking 70# petroleum asphalt, SBS-modified asphalt, and extracted old asphalt mastics as objects, the fatigue self-healing test and fracture self-healing test were conducted to simulate the intermediate-and low-temperature healing behaviors of different asphalt mastics. The impact of healing time, healing temperature, and aging degree of mastics on the healing performance was systematically investigated. The results show that the original unaged asphalt mastics present excellent fatigue healing properties with an index of 0.796 and 0.888 for 70# petroleum and SBS-modified asphalt mastics, respectively. The secondary aging process causes significant impact on the healing properties, leading to a great drop in the corresponding index, which decreased to 47.5% and 72.5% of that of the unaged ones. The fracture healing ability of all mastics was much inferior to the fatigue healing. After secondary aging, the fracture healing index values of 70# petroleum asphalt, SBS-modified asphalt, and extracted old asphalt mastics were all as low as around 0.3, indicating similar performance can be found in the secondary aged SBS-modified asphalt mastics and 70# asphalt mastics. Overall, after secondary aging, the fatigue damage of SBS-modified asphalt mastics can be cured effectively by self-healing, but the fatigue and fracture self-healing properties of 70# asphalt mastics are difficult to recover. These results could provide an innovative view to understand the fatigue and fracture healing characteristics of recycled asphalt pavement after secondary aging. [ABSTRACT FROM AUTHOR]

The present study aimed to understand the impact of inert-active filler combinations on cracking and resistance of asphalt mastic using work of fracture approach. A control grade asphalt binder (VG-30) and three fillers (inert: basalt (B); active: hydrated lime (HL) Nano hydrated lime (NHL)) were considered. The HL and NHL were added from 0% to 20% at 5% increment rate by weight of binder. The dosages of B were adjusted with respect to specific filler to binder ratios (0.6 to 1.2). The study focused on the influence of NHL on cracking resistance of mastic by means of ductile and fracture behaviour, evaluated using double edge notched tension test (DENT) at intermediate temperature condition. Findings indicated a beneficial impact in improving the cracking and fracture resistance of mastic due to reduction in the size of HL (NHL). The results signify that both HL and NHL can enhance the resistance to withstand ductile failure and fracture. Also, mastic prepared with B-NHL can be less susceptible to fracture over B-HL and hence, possessed improved ductile properties. Consequently, a lower dosage of NHL found to be superior over a higher dosage of HL in improving the cracking and fracture resistance of asphalt mastic. [ABSTRACT FROM AUTHOR]

This paper investigates the potential contribution mechanisms of steel slag fillers in asphalt mastic, covering asphalt-filler interaction mechanisms, microwave heating efficiency, electromagnetic absorption mechanisms, and fatigue durability. The physico-chemical microscopic mechanisms of the steel slag filler, the limestone filler and the interactions between the fillers and the styrene-butadiene-styrene (SBS)-modified binders were characterized. The microwave-heating efficiency of steel slag-based asphalt mastic (SBS-SS) and limestone-based asphalt mastic (SBS-LS) was quantified. The dielectric behaviour of the fillers and the corresponding mastic was further characterized to reveal the electromagnetic mechanisms associated with the microwave heating technology. The stiffness evolution and the fatigue durability of SBS-based bitumen under the effectiveness of steel slag and limestone fillers were assessed by the viscoelastic continuum damage theory model and dissipative energy approaches. The steel slag fillers exhibited a greater potential to promote microwave heat efficiency than the natural stone fillers due to higher ferric oxide compositions. SBS-SS mastics have an overall greater dielectric constant and loss factor than those of SBS-LS mastics, resulting in superior electric field energy storage and conversion capabilities. The addition of steel slag fillers magnifies the load sensitivity of the bitumen and weakens the fatigue impedance and fatigue life of asphalt mastic composites. [ABSTRACT FROM AUTHOR]

Asphalt pavements are continuously subjected to cyclic temperature variations induced by varying day–night and seasonal temperatures. However, the effect of thermal cycling on asphalt materials has not been thoroughly documented. This study conducted accelerated thermal cycling tests on asphalt mastics to simulate the environmental temperature variation. The evolution of the rheological properties and phase behaviors under cyclic temperature variations was clarified. The temperature factors sensitive to damage were identified by establishing the quantitative relationship between the cyclic temperature parameters and these properties. Results demonstrated that, as the expansion of cyclic temperature ranges, the three asphalt mastics gradually lost their viscosity properties and became increasingly elastic. Thermal cycling increased the stiffness and high temperature deformation resistance of the three asphalt mastics, but significantly reduced their stress relaxation capability. The phase structures were degraded upon thermal cycling, weakening the asphalt-aggregate interaction. The temperature difference and cyclic high temperature were the primary factors affecting the rheological performance of the asphalt mastics. SBS modified asphalt mastic displayed remarkable resistance to thermal cycling, demonstrating its potential for application in regions with frequent temperature fluctuations. This research can help us understand the evolution of asphalt pavement performance in areas with frequent temperature changes at a macro-level. [ABSTRACT FROM AUTHOR]

Asphalt mastic (bitumen + filler) plays an essential role in the fatigue performance of asphalt pavements. The time sweep test is one of the bestknown test methods for assessing fatigue performance, but fracture initiation in the specimen and the high stiffness of the mastic may bias results. These problems can be avoided with a hyperbolic specimen, but this test geometry is still largely unexplored. Therefore, 20 different asphalt mastic mixes were tested with the dynamic shear rheometer and hyperbolic specimen shape to identify the impact of various fillers and their properties, moisture, and aging on fatigue performance. These results were compared with the findings in the literature to investigate the applicability of this novel test method. Thus, a correlation could be derived between the fractional void and the fatigue performance of asphalt mastic. As also described in the literature, moist filler or water stored mastic reduce fatigue performance. [ABSTRACT FROM AUTHOR]

We examine the effect of sample geometry and analysis procedures on the fatigue life results of asphalt mastics obtained using the linear amplitude sweep (LAS) test. Asphalt mastic samples are prepared using two fillers (Red mud and Limestone), one base binder (VG-30) and three filler binder (F-B) ratios (0.5, 1, and 1.5 by weight (w/w)). The LAS test is conducted on mastic samples using cylindrical and hyperbolic geometry at three different temperatures (+10 ∘C, +20 ∘C, and +30 ∘C). We use the dissipated energy (DE) based approach, pseudo-strain energy (PSE) based approach, and R-based approach to calculate the fatigue life of asphalt mastic samples. The fatigue ranking of asphalt mastics at varying temperatures for each test geometry is found to be independent of the analysis procedure. PSE-based approach gives the highest fatigue life followed by DE- and R-based approaches, respectively. The effect of geometry is quantified using the variation of dissipated energy versus strain level. This study suggests that the LAS test can only characterize the accurate fatigue performance of the asphalt mastic if the amplitude of the complex modulus is less than 20 MPa. Hyperbolic geometry is found to be more effective in the quantification of fatigue damage of asphalt mastics. [ABSTRACT FROM AUTHOR]

The utilization of reclaimed asphalt pavement (RAP) could reduce the cost of pavements containing epoxy polymer (EP) materials. This study was aimed at improving the homogeneity of an EP-reclaimed asphalt mixtures (ERAMs) at both the micro- and meso-scale to provide a reference for an ERAM production process. At the microscale, nanoindentation tests were conducted to characterize the diffusion between the EP and aged asphalt mastic. At the mesoscale, computerized tomography (CT) X-ray scanning and MATLAB analysis were employed to investigate the distribution of the aggregate within the ERAM. The results revealed that mixing temperature played a significant role in the diffusion and distribution between the EP and the aged asphalt mastic, thus impacting the mechanical properties of the material. Heating at 180 °C (the recommended mixing temperature of EP) resulted in a wider blending zone between the EP and the aged asphalt mastic compared to heating at 160 °C (the usual mixing temperature of ordinary reclaimed asphalt mixtures). The overall dispersion of the aggregate in the ERAM exhibited greater homogeneity in the vertical direction than in the horizontal direction. Adjusting the gradation of the RAP was found to be effective in reducing horizontal variability in the distribution of the coarse aggregate, fine aggregate, and air voids in the ERAM. Adjusting the RAP gradation further enhanced the vertical homogeneity in the distribution of the fine aggregate, while its impact on the vertical distribution of the coarse aggregate was minimal. Short-term aging led to increased variability in the distribution of the coarse aggregate, fine aggregate, and air voids within the ERAM. However, adjusting the gradation was effective in mitigating the adverse effects of short-term aging on both horizontal and vertical homogeneity in the aggregate distribution. [ABSTRACT FROM AUTHOR]

To evaluate the possibility of using phosphorus slag powder instead of mineral powder as a filler in asphalt mastic, this study investigates the micro-characteristics of phosphorus slag powder and its viscoelastic mechanical properties in asphalt mastic. A systematic approach combining macro and micro test methods was used to analyze the physical and surface characteristics, void structure, and surface energy of phosphorus slag powder. The viscoelastic mechanical properties of phosphorus slag powder were evaluated using appropriate indexes. Meanwhile, the correlations between and limitations of various evaluation indexes and the high-temperature rheological properties were identified. The results demonstrate that phosphorus slag powder exhibits low density, small overall particle size, difficulty in forming agglomerates, developed pores, large specific surface area, and high surface energy, which is suitable for replacing mineral powder as a filler in asphalt mastic. The main factors affecting the viscoelastic properties of asphalt mastic are the particle size and dosage of phosphorus slag powder. Generally speaking, phosphorus slag powder asphalt mastic with particle sizes ≤ 18 μm exhibits the best performance. In practical engineering applications, the appropriate dosage (7%, 10%, 13%) can be selected based on different regions and specific design and construction requirements. Additionally, zero-shear viscosity (ZSV), non-recoverable creep compliance (Jnr), and creep recovery percentage (R) exhibit a strong correlation with the high-temperature rheological properties of asphalt mastic. At the same time, the rutting factor (G*/sin δ) presents certain limitations.

Asphalt is a kind of high viscosity material with fluidity under certain conditions, which results in the healing function to repair small cracks of asphalt pavement by itself, and thus prolonging the service life of the pavement. With the aging process, the flow behavior of asphalt will gradually deteriorate and synchronously impact the self-healing performance. To gain a deeper understanding of the changes in asphalt's performance characteristics after aging, Fourier transform infrared spectroscopy tests, Frequency scanning tests, and Fatigue-healing-fatigue tests were conducted to examine the changes in flow behavior and self-healing properties of asphalt enduring secondary aging. The results showed that SBS modified asphalt presented superior anti-aging performance compared to base asphalt, since the SBS modifier can effectively prevent the formation of sulfoxides and carbonyl groups in asphalt. However, SBS modifier will also inhibit the flow behavior of asphalt due to its complex three-dimensional spatial structure, leading to a decrease in flow behavior index from 0.967 for unaged base asphalt to 0.672 for SBS modified asphalt, respectively. Furthermore, both of the flow behavior and self-healing performance will be affected by aging process. After secondary aging, the flow behavior index of base and SBS modified asphalt decreased by 9.8 % and 12.1 % compared to the corresponding virgin asphalt mastics, respectively, while the self-healing performance decreasing by 83.9 % and 57.6 %. These findings provide an innovative perspective for secondary recycling research and application of asphalt pavements.

Pavement structures experience stresses due to temperature changes, and these stresses gradually dissipate, similar to the rheological phenomenon of stress relaxation. In this study, we conducted various tests, including low-temperature stress relaxation, low-temperature bending beam rheology test, glass transition temperature test, and asphalt single-edge-notch bending test, to compare and analyze the relaxation performance and low-temperature crack resistance of asphalt mastics. Using the SPSS method, we investigated the correlation between the relaxation performance and low-temperature crack resistance of asphalt mastics. The results revealed that the relaxation time and rate obtained in the small beam bending test were reliable indicators for evaluating the relaxation performance of asphalt mastics. Moreover, the relaxation performance of asphalt mastics exhibited a strong linear relationship with low-temperature crack resistance, as evidenced by the asphalt performance ranking. Through multiple linear regression analysis of relaxation properties, we derived a prediction equation for the low-temperature cracking resistance of asphalt mastics.

In this study, basalt fiber having two types of diameters (16 μm and 25 μm) was selected and added to asphalt mastic and asphalt mixtures using different fiber proportions. The influences of fiber diameters and proportions on the properties of asphalt mastic and mixtures were studied. The adhesion behavior of the fiber-asphalt mastic (FAM) interface was evaluated by a monofilament pullout test, and the rheological properties of FAM were evaluated by temperature sweep, linear amplitude sweep, and bending beam rheological tests. In addition, the high-temperature stability, intermediate and low-temperature cracking resistance, and water stability of fiber-modified mixtures were studied by wheel tracking, ideal cracking, a low-temperature bending beam, and a water-immersed Marshall test. The results showed that the interface adhesion behavior between 16 μm fiber and asphalt mastic was more likely in the fiber failure mode at both −12 °C and 25 °C. Adding basalt fiber can significantly improve the high-temperature and fatigue properties of asphalt mastics. Moreover, 16 μm fiber had a better modifying effect on asphalt mastic than 25 μm fiber. The same enhancement trend can be observed in asphalt mixtures. Basalt fibers with 16 μm diameters can improve the high-temperature performance of asphalt mixtures more significantly. In addition, 16 μm fiber could sharply enhance the cracking performance of the mixtures at intermediate and low temperatures, while the enhancing effect of 25 μm fiber on the mixture is insignificant, though both diameters of the fibers have a minor effect on the water stability. [ABSTRACT FROM AUTHOR]

The volatilization of asphalt fumes not only affects the health of construction workers, but also damages the environment. It even affects the construction quality of asphalt pavement in tunnels. This article focuses on solving the emission of asphalt fumes to better protect human health and the environment, while satisfying the use of asphalt pavement. A flame retardant and smoke suppressant (compound) with Mg(OH)2 as the main component was developed, and flame retardant asphalt mixture and asphalt mastics were prepared to evaluate the flame retardant and smoke suppressant properties and performance effects. Firstly, its low- and high-temperature performances were investigated with BBR and DSR, respectively. Then, the indoor combustion test and the cone calorimeter test were used to evaluate the fire retardant smoke suppression effect of the asphalt mastic. Thirdly, the flame retardant effect of asphalt mastic mixed with the compound was further analyzed by the TG test and SEM. The pyrolysis temperature, mass loss, and microscopic state of the asphalt surface were used to verify and explain the flame retardant reaction effect and process of the compound. Finally, the asphalt mixture performance was evaluated, as well as the flame retardant smoke suppression effect by asphalt mixture combustion tests. The results showed that the flame retardant smoke suppression time of the flame retardant asphalt mixture was reduced by 66%, and the smoke emission area was reduced by 20%. The flame retardant smoke suppression effect of the asphalt mixture was improved by 44%. It is proven that this kind of fire retardant and smoke suppressing asphalt mastic and mixture met performance needs in use, and the fire retardant and smoke suppressing effect was obvious. This solution addresses the issue of asphalt smoke generated during the construction of asphalt pavement, providing better support for the construction of asphalt pavement in tunnels. [ABSTRACT FROM AUTHOR]

In order to evaluate the interaction ability between anti-icing agent and asphalt, and reveal the interaction mechanism，rheological properties of anti-icing agent asphalt constructed by sigmoidal function and WLF equation. The interaction ability between anti-icing agent and asphalt was evaluated based on the coefficient C of Palieme model. The interaction micro-mechanism was analyzed by using SEM and AFM experiment. The results show that anti-icing agent exhibits a weaker interaction ability with asphalt by the comparison of coefficient C. The limestone powder asphalt slurry has a bee structure，forming a dense intertwined network system while the anti-icing agent is uniformly dispersed in asphalt mastic by absorbing the light components, without bee-shaped structure. Overall，the influence of anti-icing agent on the ice and snow melting performance and road performance of asphalt mixture，the anti-icing agent should not replace mineral powder altogether. [ABSTRACT FROM AUTHOR]

Fly ash is one of the industrial waste residues with significant emissions in China, and its rational utilization has important economic significance and environmental value. Due to the similarity in properties between fly ash and limestone mineral powder, it is possible to replace the mineral powder filler in asphalt concrete with fly ash. This article explored the feasibility of replacing the mineral powder with fly ash in an asphalt mixture through the study of fly-ash-modified asphalt mastic. Firstly, the microstructures and elemental compositions of fly ash and mineral powder were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. Then, the rheological properties of asphalt mastics with different fillers were studied using dynamic shear rheological (DSR) tests. The results show that when the stress level was 3.2 kPa, the change in the Jnr value was different from that at 0.1 kPa, indicating that after increasing the stress level, the Jnr of fly ash asphalt mastic was smaller, and fly ash can improve the high-temperature creep performance of asphalt mastic. Replacing mineral powder with fly ash can improve the high-temperature rheological properties of asphalt mastic, but this damages the elastic and crack resistance properties of the asphalt mastic. In practical applications, partial substitution of mineral powder can be considered for the preparation of an asphalt mixture. [ABSTRACT FROM AUTHOR]

Integrating fibers into asphalt mixtures improves their crack resistance and permanent deformation. Previous studies have found the effect of various fibers on asphalt mixtures, but bamboo fibers were not included. In addition to providing strength and toughness, bamboo fiber's recycled nature saves resources and protects the environment. This study investigates the reinforcement effect by different particle sizes and contents of bamboo fiber on asphalt mastic. Three sizes (100 mesh, 200 mesh, and 400 mesh) and three contents (3%, 6%, and 9%) of bamboo fibers were selected to modify the asphalt mastic. The frequency sweep (FS), linear amplitude sweep (LAS), multiple stress creep recovery (MSCR), and bending beam rheometer (BBR) test were used to evaluate the linear viscoelastic properties, fatigue performance, rutting resistance, and cracking resistance of fiber-modified asphalt mastics, respectively. Results demonstrate that bamboo fibers have excellent stiffness-reinforced characteristics, increase the elasticity of the asphalt, and enhance the high-temperature stability and low-temperature crack resistance of the asphalt mastic but adversely affect the fatigue properties of the asphalt mastic. In addition, asphalt mastics exhibited the same crack initiation stage and different crack expansion behavior, and the fiber incorporation prevented further crack propagation. Burgers model was used to represent the rheological behaviors of the asphalt mastic with bamboo fiber, and the model parameters are estimated. Furthermore, the Burgers model results indicated that the fiber addition reduced the proportion of elastic compliance and viscous compliance but increased the proportion of delayed elastic compliance of the asphalt mastic. Finally, the statistical model obtained based on the statistical approach can appropriately fit the values of rheological parameters with different fiber contents and lengths. The optimal design solution is 200 mesh with 9% content. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate different types of zinc production wastes for using as filler in asphalt mixtures. Four different types of waste, namely, leach cake, nickel cake, cobalt cake and zinc ash have been chosen along with limestone powder as the control filler for evaluation. Elemental analysis of the fillers, the rheological properties of the mastics and some mechanical properties of the mixtures using Marshall and indirect tensile strength (ITS) tests and their environmental effects using Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) tests have been investigated. Results show that, except the nickel cake, for which the cadmium concentration exceeds the legal limit, rest of the fillers can be used as filler in asphalt concrete. The zinc ash filler results in much better performance than the other fillers. Leach and cobalt cake are found to be hydrophilic with low resistance against moisture damage. [ABSTRACT FROM AUTHOR]